Thanos wanted the infinity stones, which can make anything true, to wish half the universe to die. In the movies, he did this to curb overpopulation so that the universe's resources wouldn't be drained. After he succeeded, he destroyed the stones.

For resources to run out they have to be finite. His idea is stupid because populations would rise again to previous levels in a few centuries, so nothing would be accomplished beyond delaying the inevitable for a geologically insignificant time. Since things will run out anyways, all he's doing is making people more miserable by killing the survivors' loved ones.

Apparently, in the comics, he loved the goddess of death or something, and he wanted to create death as a tribute to gain her love.

Thanos wanted the infinity stones, which can make anything true, to wish half the universe to die. In the movies, he did this to curb overpopulation so that the universe's resources wouldn't be drained. After he succeeded, he destroyed the stones.

For resources to run out they have to be finite. His idea is stupid because population would rise again to previous levels in a few centuries, so nothing would be accomplished beyond delaying the inevitable for a geologically insignificant time. Since things will run out anyways, all he's doing is making people more miserable by killing the survivors' loved ones.

Apparently, in the comics, he loved the goddess of death or something, and he wanted to create death as a tribute to gain her love.